The present invention relates to an indicator for showing the product lifetime of the item to which said indicator is attached. More particularly the present invention relates to an indicator which, on activation by applying pressure, measures elapsed time and displays visual indications relating to the product lifetime of the item to which it is attached.
The need to monitor the lifetime of food and drug products is well known, especially where such products deteriorate rapidly after manufacturing or opening. Milk-based products deteriorate rapidly from the time of manufacture, and many types of long-life products (such a canned produce) need to be disposed of within days of opening. Thus, a typical home environment needs a means of monitoring the freshness of the products in the refrigerator. In particular, in situations in which a can is opened or a foodstuff prepared but not consumed immediately in its entirety, the remains will often be placed in a container in the refrigerator. In the absence of a simple aid to show the consumer how long any such container has been in the refrigerator, the danger exists that said remains will deteriorate and pose a health risk. Alternatively, being unaware of how long this package has been in the refrigerator, the over-cautious consumer may dispose of the contents before this becomes necessary. In either case, the need for a simple, inexpensive and reliable indicator or tag for such containers in the refrigerator is clear.
A number of means to accomplish this objective are well known in the art. Co-pending application WO 01/26993, describes a cap containing an integral lifetime indicator where the first opening of the cap causes the activation of the lifetime indicator. However, this approach does not assist the consumer who is preparing a container of “left-overs” within the consumer's premises. Similarly, U.S. Pat. Nos. 4,292,916; 5,053,339; 5,446,705 and 5,633,835 describe colour changing devices for monitoring the shelf-life of perishable products. These devices are initiated by physically bringing into contact reactive layers so that a chemical reaction between them will start, and this action can only conveniently be performed at the time of initial manufacturing. While this approach is suitable for monitoring the degradation of foodstuffs throughout the entire distribution chain, they are unsuitable for user activation and application within the home environment. Further prior art addresses issues associated with applying such devices during the manufacturing and packaging processes. U.S. Pat. No. 5,555,223 describes a process for attaching timing indicators to packaging, including the step of setting the timer's clock at the exact time of production. Thus the above prior art devices require special manufacturing steps at the production-end of the packaging and filling processes, rather than the end-user affixation and activation of a lifetime indicator at the time of use or of storage as envisaged in the current invention. Similarly, time-temperature indicators (TTIs) also address the task of monitoring the entire distribution chain, rather than providing an end-user solution. A number of liquid migration technologies are known in the art, but these typically rely either on the rapid wicking of paper and are thus good for time ranges in the minutes to hours range, or require complex fabrication of the migration media from materials such as gelatine or other gels in order to provide for slower migration, and are thus both complex and expensive to produce.